Hydrocarbon fuel



United States Patent HYDROCARBON FUEL John W. Bishop, Westfield, N.J.,assignor to Tide Water Associated Oil Company, Bayonne, N.J., acorporation of Delaware No Drawing. Application August 17, 1955 SerialNo. 529,074

5 Claims. (CI. 44-69) This invention relates to a hydrocarbon fuel forinterproved hydrocarbon fuel for use in spark ignition engines toimprove the performance thereof by reducing certain harmful effects dueto engine deposits which form in the operation of modern highcompression engines.

With the advent of the high compression engine and the progressiveincrease in compression ratios in recent years, certain problems havedeveloped in the operation of these engines. One of the most annoyingand critical of these problems has been knocking of the engines in use vsufiicient to inhibit surface ignition. Other objectives,

. and spark plug fouling. Certain of these additives actunal combustionengines and, more particularly, to an imand rough operation undercertain conditions, particularly during acceleration and at idlingspeeds. These undesirable characteristics result primarily from depositswhich form in the upper cylinder area as unburned residue of the fuel.

Knocking or pinging, as it is sometimes called, results from severalcauses. The knocking phenomenon known as detonation normally resultswhen the engine has built up top cylinder deposits to extent that itsoctane requirement exceeds the octane quality of the gasoline employed.Detonation can be reduced or eliminated by raising the octane number ofthe gasoline through increas- !ing the percentage of tetraethyl leadtherein or by employing improved refining methods in manufacture of thegasoline or both.

Another type of knocking which is encountered in modern engines is knownas surface ignition. This type of knocking results from abnormalcombustion of the fuel in the combustion chamber wherein the fuel isignited by incandescent surfaces of deposits therein at a time otherthan that at which the spark plug fires. Such abnormal firing of thecharge by surface ignition can be expected to result in a loss of powerand rough operation of the engine.

In the case of automobile engines, both surface ignition pinging anddetonation pinging are annoying to the motorist and it is desirable toeliminate such noises or to reduce them to a level where they areinaudible. As indicated above, detonation can be controlled by raisingthe octane value of the fuel. However, in the event that an engine isknocking because of surface ignition but not because of detonation, i.e.surface ignition-limited but not detonation-limited, which is the casein many instances of engines usage today, it is desirable to provide asimple means for inhibiting surface ignition without resorting to therelatively expensive expedients of increasing the tetraethyl leadcontent and use of additional restantially less than that of theanti-detonating agent but ally have been found to increase top cylinderdeposits and to raise the octane requirement of the engine,necessitating the use of a gasoline of higher octane value in order tosuppress knocking. Insofar as I am aware, none of these additives arecompletely effective in eliminating surface ignition.

In accordance with the present invention a motor fuel particularlyadapted for spark ignition engines has been developed by dissolving ingasoline, and especially in gasoline containing the usual tetraethyllead anti-detonating compositions, certain molybdenum compoundswhich aresoluble in effective concentrations in the gasoline. Hydrocarbon-solublecompounds of molybdenum which fall within a metallo-organo typestructure in which the molybdenum is connected through oxygen to anorganic radical are particularly effective. More specifically, they areof the class of compounds in which the molybdenum is connected throughoxygen to an organic acid residue and are prepared by reacting amolybdenum compound with an acid hydrogen. Examples of molybdenumorganocompounds of this category are molybdenum salts of organic acids, suchas molybdenum salts of the fatty acids as oleic, stearic and the like,and molybdenum salts of the naphthenic acids. Other compounds ofmolybdenum which are effective are certain phenates and derivativesthereof containing molybdenum, particularly phenates in which one ormore of the phenoxy radicals carries substituent alkyl groups.

The beneficial effect of compounds of molybdenum is readilyascertainable in test engine runs as will be apparent from thedisclosure appearing hereinbelow when such compounds are incorporated inleaded gasolines such as those presently available to the public for theoperation of modern high compression engines. In such gasolines themolybdenum decomposition products resulting during burning of gasolinein the engine appear, in addition to suppression of surface ignition, tohave the property of combining with the lead and also with any sulfurpresent. in .the gasoline and scavenging these elements to some degreefrom the compression chamber. It would also appear that as an additionalfunction the molybdenum sulfide formed during combustion of a sulfurcontaining gasoline may operate to improve the lubrication of thecylinder walls, rings and other moving parts. Thus, the particularmolybdenum compounds here under consideration appear capable ofperforming multiple functions when incorporated in motor fuel insuitable proportions.

The following examples are intended to set forth specific embodiments ofthe invention with no intent necessarily to limit the invention to theuse of the specific compositions disclosed therein. In the examples themolybdenum compounds noted therein were dissolved in a commercialgasoline manufactured for use in automobile engines and refined fromEast Texas and Gulf Coast crudes by conventional refining methods. Thisgasoline contained 2.8 mL/gallon of conventional tetraethyl leadanti-detonating composition and had a Research octane rating of 94.

The fuel in which these molybdenum compounds had been incorporated wasused to operate a test engine especially adapted for detecting surfaceignition. This engine is a CFR supercharged (F4) engine having ashrouded intake valve and fitted with a conventional spark plug andignition system and with an additional spark plug in which the sideelectrode has been removed. The latter plug provides an ionization gapand is electrically connected during the test runs to a depositeignition counter manufactured by the Erwin Scientific InstrumentCompany. The deposit ignition counter, when so connected and operated,indicates and counts all explosions occurring within the cylinder exceptthose which occur as a result of the firing of the spark plug. Suchexplosions are detected by the deposite ignition counter as a result ofcurrent flowing across the gap in the modified spark plug throughionized gases caused by the surface ignition firing of the combustioncharge. With this equipment the number of surface ignitions per unit oftime can be accurately measured during operation of the engine.

The above-described single cylinder engine had a compression ratio of9.0 to l with a spark setting at top dead center of the piston travel.During. each test run the engine was operated on the test fuel for amaximum of 40 hours at a speed of 1 800 r.p.m. and while maintainingthetemperature of the cooling jacket at 212 F. and the temperature ofthe intake air at 250 F. The crankcase lubricant employed was a refinedhydrocarbon crankcase lubricating oil of 450 SUS viscosity at 100 F.consisting of 100 percent distillate lubricating oil containing noadditives.

In order to approach normal driving conditions for automobile enginesthe test engine was operated throughout each run alternately under lowduty conditions for 19.5 minutes and high duty conditions for 0.5minute. During the low duty cycle the supercharge pressure was adjustedso that the absolute manifold pressure was equivalent to 20 inches ofmercury at an air to fuel ratio of 13 to 1. High duty cycle conditionswere adjusted to give an absolute manifold ratio equivalent to 30 inchesof mercury and an air to fuel ratio of 14 to 1. The low duty cyclepermitted the engine to build up deposits in order to encourage surfaceignition during the subsequent high duty cycle, the latter being underhigh power output conditions at which the engine containing suchdeposits would be more likely to exhibit surface ignition.

In conductance of the engine tests referred to herein, deposits wereremoved from the combustion chamber of the test engine before commencingeach run in order that all runs were started under similarly cleanengine conditions.

Example I The above-described engine was operated in a first 40 hourtest under the above stated conditions using as basefuel the commerciallead gasoline described above. The average number of surface ignitioncounts per hour indicated by the deposit ignition counter was 49. Thisrun constituted a standardization run for the base gasoline containingno molybdenum additives and no additives other than the conventionaltetraethyl lead composition incorporated by the refiner.

Example 11 There was dissolved into the above-specified base gasoline ofExample I 0.2 percent by weight of molybdenum naphthenate. This amountwas equivalent to 0.2 theory based upon the lead content. The molybdenumnaphthenate contained percent by weight of molybdenum and was preparedin known manner by reacting M0 0 with commercial naphthenic acid of 220acid number. The resulting solution produced a gasoline compositionhaving a distinctive reddish-purple color.

The test engine was operated using as fuel this gasoline compositionunder the conditions set forth hereinabove while counting the number ofsurface ignitions throughout a 40 hour run. The average number ofsurface ignitions registering on the counter during this run was 2counts per hour. This indicates an extremely great reduction, in fact avirtual elimination, of surface ignition due to the presence of themolybdenum compound 4 in the fuel employed, as is clearly evident fromcomparison with the test results of Example I on the base gasoline.

Example Ill The molybdenum compound used in this example wastri(tertiary amyl phenoxy)molyb denum dichloride. This molybednumphenate was prepared by reacting molybdenum pentachloride with tertiaryamyl phenol under conditions which are known to produce the phenate.Using as fuel the base gasoline containing 0.07 percent (0.2 theory) ofthis molybdenum phenate a run was made as above-described in the testengine with the result that the average number of surface ignitioncounts per hour in this case was 1.5, thus indicating the extremeeffectiveness of this additive in reducing surface ignition.

The following table discloses data obtained using the above-describedtest engine and test conditions in which the base fuel contained, inaddition to conventional tetraethyl lead anti-detonating agent, also thevarious additives listed in the table. Periodic standardization runswere made using the base gasoline in order to confirm the surfaceignition tendencies of the base gasoline and the condition of theengine. These standardization runs exhibited average numbers of surfaceignitions per hour of 49, 40.5, 51, 37, 40 and 42, respectively, thusindicating that the base fuel and engine combination maintained auniformly high level of surface ignition (43.2 average). The tabulateddata below include the results of the runs in the above examples forcomparison purposes.

Base Gasoline (2.8 ml. of TEL/gal.) Plus Indicated Additive AverageCounts Per Hour NINNN 0.05 theory tri(tertiary amyl phenoxy) molybdenumdichloride (0.018%) Base gasoline (no molybdenum additive) 1 36 hourrun. I 24 hour run. 3 Average 6 runs.

The outstanding effectiveness of the molybdenum compounds in reducingsurface ignition is evident from the above examples and tabulated datawhich shows a material reduction in surface ignition counts for thegasoline of this invention over the commercial leaded gasoline whichformed the base thereof and a striking improvement over certaincompounds of other metals as zirconium and phosphorus, the latter ofwhich have been used or proposed as gasoline additives.

The molybdenum compounds of this invention are markedly effective inreducing surface ignition when dissolved in motor fuel in relatively lowproportionate amounts and an important concept resides in the discoverythatsuch small proportionate but effective amounts can be employedwithout causing seriously objectionable side effects which often attenduse of certain known additives. As indicated in the above test data,surface ignition may be practically eliminated when using in asparkignition engine, gasoline containing molybdenum compounds inconcentrations as low as 0.05 percent by weight with little lessening ofthe effect when the amount is reduced to 0.01 percent. A practicalreduction in surface ignition is indicated for concentrations as low asabout 0.001 percent. The lower concentrations are preferred for severalspecific reasons; first because of relatively low material cost andsecond, because at the lower concentrations there is less tendency ofmetal additives in general toward formation of engine deposits in useand less tendency toward formation of precipitates in the fuel prior touse. Regarding the latter elfect, Lawson engine runs using the fuel ofthis invention indicate no objectionable deposit formation in leadedfuels containing up to about 0.2 percent molybdenum compounds of thetype herein disclosed. Although this concentration, as shown in theabove data, is extremely effective in inhibiting surface ignition, it ispreferred to employ these additives in lower proportionate amounts inthe fuel, as for example at about 0.01 percent or lower since at orbelow 0.01 percent concentrations little if any tendency towardsinstability is exhibited by gasoline containing such amounts andsatisfactory surface ignition inhibition is obtained.

The disclosed molybdenum compounds in the abovespecified proportionateamounts did not appear to materially affect the octane rating of thegasolines in which they were incorporated. Use thereof in the engineruns set forth hereinabove did not cause dirty engine conditions.

That specific embodiment of this invention residing in hydrocarbon fuelscontaining molybdenum compounds in which the molybdenum atom isconnected through oxygen to organic radicals is believed unique, ascompared to known fuels allegedly containing dissolved molybdenumcompounds of different molecular structure, in exhibiting relatively lowtendency towards hydrolysis of the molybdenum additive and in possessingother distinguishing features and advantages.

The incorporation of molybdenum compounds in leaded gasoline inrelatively small amounts results in an incidental but neverthelesseconomically important advantage in imparting to the fuel a distinctivecolor. It is thus within the broader concepts of this invention toprovide a leaded hydrocarbon fuel containing any dissolved molybdenumcompound capable of imparting color to the resulting solution, to thusreplace all or a portion of the conventional dye required for theseleaded gasolines which at the same time is effective to improve suchgasoline in one or more of the respects disclosed elsewhere herein.

With further reference to the molecular composition of compounds of thephenate structure, there are contemplated, as included within theconcept of the invention, such molybdenum phenates as contain at leastone aromatic radical connected to molybdenum through oxygen and whereinthe remaining valences of the molybdenum atom are satisfied by otherradicals. Likewise substituent groups on the rings of the phenate may beof any suitable carbon chain length as long as the compound as a wholeis sufficiently soluble in the hydrocarbon fuel in amounts to impartfuel icproving effectiveness.

1 claim:

1. A motor fuel composition consisting essentially of gasoline havingdissolved therein, in an amount effective to reduce the surface ignitiontendency of said gasoline, a molybdenum compound selected from the groupconsisting of molybdenum naphthenate and tn'(tertiary amyl phenoxy)molybdenum dichloride.

2. A motor fuel composition as defined in claim 1 in which the saidmolybdenum compound is present in amount by weight of between about0.001% and 0.02%.

3. A leaded gasoline having dissolved therein between about 0.01 theoryand about 0.2 theory of molybdenum naphthenate.

4. A leaded gasoline having dissolved therein between about 0.05 theoryand about 0.2 theory of tri(tertiary amyl phenoxy) molybdenumdichloride.

5. A leaded gasoline having dissolved therein an alkyl phenoxymolybdenum chloride in amount effective to reduce the surface ignitiontendency of said gasoline.

References Cited in the file of this patent UNITED STATES PATENTS1,779,061 Danner et al Oct. 21, 1930 2,086,775 Lyons et a1. July 13,1937 2,151,432 Lyons et a1 Mar. 21, 1939 FOREIGN PATENTS 684,887 FranceJuly 2, 1930 UNITED STATES. PATENT OFFICE CERTIFICAT OF C) ,.ECON

Patent No, 2,881,662 April '7, 1959 John W Bishop It is hereby certifiedthat error in above numberei patent requiring eorrentio that seiclLetters Patent should read as corrected below,

In the grant, 2 and I, for "ass'ignor to Tide Water Aseoeiated OilCompany, of Bayonne, New Jersey, a corporation of Delaware," readass'ignor to Tidewater Oil Company, a corporation of Delaware, line 1-2,for "Tide Water Associated Oil Company, its successors" read meTidewater Oil Company, its. successors in the heading to the printedspecification, lines 3 to 5, for essignor to Tide Water Associated OilCompany, Bayonne, N; J, a corporation of Delaware" read assignor toTidewater Oil Company, a, corporation of .Uelaware' column 1, line 59,for "engines" read engine column 6, line 10, for ioproving" readimproving Signed and sealed this 11th day of August 1959,.

. (SEAL) Attest:

KARL AXLINE v ROBERT (3.. WATSON Attesting Officer I Comissioner ofPatents

3. A LEADED GASOLINE HAVING DISOLVED THEREIN BETWEEN ABOUT 0.01 THEORYAND ABOUT 0.2 THEORY OF MOLYBDENUM NAPHTHENATE.
 4. A LEADED GASOLINEHAVING DISCOLVED THEREIN BETWEEN ABOUT 0.05 THEORY AND ABOUT 0.2 THEORYOF TRI(TERIARY AMYL PHENOXY) MOLYBDENUM DICHLORIDE.